code: def naive_concordance_index(
      event_times, predicted_event_times, event_observed=None
  ) -> float:
      (
          event_times,
          predicted_event_times,
          event_observed,
      ) = _preprocess_scoring_data(
          event_times, predicted_event_times, event_observed
      )
      return _concordance_ratio(
          *_naive_concordance_summary_statistics(
              event_times, predicted_event_times, event_observed
          )
      )
  
file_path: lifelines/lifelines/utils/concordance.py
imports: import numpy
  from lifelines.utils.btree import _BTree
label_desc: Use image node_id 7 for calling a global function with example usage: naive_concordance_index(event_times, predicted_event_times, event_observed) and returns: _concordance_ratio